From d658d59471ed80c4a8aaf082ccc3e83cdf5ae4c1 Mon Sep 17 00:00:00 2001 From: Jarkko Sakkinen Date: Mon, 28 Oct 2024 07:49:59 +0200 Subject: [PATCH 1/3] tpm: Return tpm2_sessions_init() when null key creation fails Do not continue tpm2_sessions_init() further if the null key pair creation fails. Cc: stable@vger.kernel.org # v6.10+ Fixes: d2add27cf2b8 ("tpm: Add NULL primary creation") Reviewed-by: Stefan Berger Signed-off-by: Jarkko Sakkinen --- drivers/char/tpm/tpm2-sessions.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c index 511c67061728..bb7b94b32c46 100644 --- a/drivers/char/tpm/tpm2-sessions.c +++ b/drivers/char/tpm/tpm2-sessions.c @@ -1347,14 +1347,21 @@ static int tpm2_create_null_primary(struct tpm_chip *chip) * * Derive and context save the null primary and allocate memory in the * struct tpm_chip for the authorizations. + * + * Return: + * * 0 - OK + * * -errno - A system error + * * TPM_RC - A TPM error */ int tpm2_sessions_init(struct tpm_chip *chip) { int rc; rc = tpm2_create_null_primary(chip); - if (rc) - dev_err(&chip->dev, "TPM: security failed (NULL seed derivation): %d\n", rc); + if (rc) { + dev_err(&chip->dev, "null key creation failed with %d\n", rc); + return rc; + } chip->auth = kmalloc(sizeof(*chip->auth), GFP_KERNEL); if (!chip->auth) From cc7d8594342a25693d40fe96f97e5c6c29ee609c Mon Sep 17 00:00:00 2001 From: Jarkko Sakkinen Date: Mon, 28 Oct 2024 07:50:00 +0200 Subject: [PATCH 2/3] tpm: Rollback tpm2_load_null() Do not continue on tpm2_create_primary() failure in tpm2_load_null(). Cc: stable@vger.kernel.org # v6.10+ Fixes: eb24c9788cd9 ("tpm: disable the TPM if NULL name changes") Reviewed-by: Stefan Berger Signed-off-by: Jarkko Sakkinen --- drivers/char/tpm/tpm2-sessions.c | 44 +++++++++++++++++--------------- 1 file changed, 24 insertions(+), 20 deletions(-) diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c index bb7b94b32c46..4821be276670 100644 --- a/drivers/char/tpm/tpm2-sessions.c +++ b/drivers/char/tpm/tpm2-sessions.c @@ -915,33 +915,37 @@ static int tpm2_parse_start_auth_session(struct tpm2_auth *auth, static int tpm2_load_null(struct tpm_chip *chip, u32 *null_key) { - int rc; unsigned int offset = 0; /* dummy offset for null seed context */ u8 name[SHA256_DIGEST_SIZE + 2]; + u32 tmp_null_key; + int rc; rc = tpm2_load_context(chip, chip->null_key_context, &offset, - null_key); - if (rc != -EINVAL) - return rc; + &tmp_null_key); + if (rc != -EINVAL) { + if (!rc) + *null_key = tmp_null_key; + goto err; + } - /* an integrity failure may mean the TPM has been reset */ - dev_err(&chip->dev, "NULL key integrity failure!\n"); - /* check the null name against what we know */ - tpm2_create_primary(chip, TPM2_RH_NULL, NULL, name); - if (memcmp(name, chip->null_key_name, sizeof(name)) == 0) - /* name unchanged, assume transient integrity failure */ - return rc; - /* - * Fatal TPM failure: the NULL seed has actually changed, so - * the TPM must have been illegally reset. All in-kernel TPM - * operations will fail because the NULL primary can't be - * loaded to salt the sessions, but disable the TPM anyway so - * userspace programmes can't be compromised by it. - */ - dev_err(&chip->dev, "NULL name has changed, disabling TPM due to interference\n"); + /* Try to re-create null key, given the integrity failure: */ + rc = tpm2_create_primary(chip, TPM2_RH_NULL, &tmp_null_key, name); + if (rc) + goto err; + + /* Return null key if the name has not been changed: */ + if (!memcmp(name, chip->null_key_name, sizeof(name))) { + *null_key = tmp_null_key; + return 0; + } + + /* Deduce from the name change TPM interference: */ + dev_err(&chip->dev, "null key integrity check failed\n"); + tpm2_flush_context(chip, tmp_null_key); chip->flags |= TPM_CHIP_FLAG_DISABLE; - return rc; +err: + return rc ? -ENODEV : 0; } /** From df745e25098dcb2f706399c0d06dd8d1bab6b6ec Mon Sep 17 00:00:00 2001 From: Jarkko Sakkinen Date: Mon, 28 Oct 2024 07:50:01 +0200 Subject: [PATCH 3/3] tpm: Lazily flush the auth session Move the allocation of chip->auth to tpm2_start_auth_session() so that this field can be used as flag to tell whether auth session is active or not. Instead of flushing and reloading the auth session for every transaction separately, keep the session open unless /dev/tpm0 is used. Reported-by: Pengyu Ma Closes: https://bugzilla.kernel.org/show_bug.cgi?id=219229 Cc: stable@vger.kernel.org # v6.10+ Fixes: 7ca110f2679b ("tpm: Address !chip->auth in tpm_buf_append_hmac_session*()") Tested-by: Pengyu Ma Tested-by: Stefan Berger Reviewed-by: Stefan Berger Signed-off-by: Jarkko Sakkinen --- drivers/char/tpm/tpm-chip.c | 10 +++++++ drivers/char/tpm/tpm-dev-common.c | 3 +++ drivers/char/tpm/tpm-interface.c | 6 +++-- drivers/char/tpm/tpm2-sessions.c | 45 ++++++++++++++++++------------- 4 files changed, 44 insertions(+), 20 deletions(-) diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c index 854546000c92..1ff99a7091bb 100644 --- a/drivers/char/tpm/tpm-chip.c +++ b/drivers/char/tpm/tpm-chip.c @@ -674,6 +674,16 @@ EXPORT_SYMBOL_GPL(tpm_chip_register); */ void tpm_chip_unregister(struct tpm_chip *chip) { +#ifdef CONFIG_TCG_TPM2_HMAC + int rc; + + rc = tpm_try_get_ops(chip); + if (!rc) { + tpm2_end_auth_session(chip); + tpm_put_ops(chip); + } +#endif + tpm_del_legacy_sysfs(chip); if (tpm_is_hwrng_enabled(chip)) hwrng_unregister(&chip->hwrng); diff --git a/drivers/char/tpm/tpm-dev-common.c b/drivers/char/tpm/tpm-dev-common.c index c3fbbf4d3db7..48ff87444f85 100644 --- a/drivers/char/tpm/tpm-dev-common.c +++ b/drivers/char/tpm/tpm-dev-common.c @@ -27,6 +27,9 @@ static ssize_t tpm_dev_transmit(struct tpm_chip *chip, struct tpm_space *space, struct tpm_header *header = (void *)buf; ssize_t ret, len; + if (chip->flags & TPM_CHIP_FLAG_TPM2) + tpm2_end_auth_session(chip); + ret = tpm2_prepare_space(chip, space, buf, bufsiz); /* If the command is not implemented by the TPM, synthesize a * response with a TPM2_RC_COMMAND_CODE return for user-space. diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c index 5da134f12c9a..8134f002b121 100644 --- a/drivers/char/tpm/tpm-interface.c +++ b/drivers/char/tpm/tpm-interface.c @@ -379,10 +379,12 @@ int tpm_pm_suspend(struct device *dev) rc = tpm_try_get_ops(chip); if (!rc) { - if (chip->flags & TPM_CHIP_FLAG_TPM2) + if (chip->flags & TPM_CHIP_FLAG_TPM2) { + tpm2_end_auth_session(chip); tpm2_shutdown(chip, TPM2_SU_STATE); - else + } else { rc = tpm1_pm_suspend(chip, tpm_suspend_pcr); + } tpm_put_ops(chip); } diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c index 4821be276670..0739830904b2 100644 --- a/drivers/char/tpm/tpm2-sessions.c +++ b/drivers/char/tpm/tpm2-sessions.c @@ -333,6 +333,9 @@ void tpm_buf_append_hmac_session(struct tpm_chip *chip, struct tpm_buf *buf, } #ifdef CONFIG_TCG_TPM2_HMAC + /* The first write to /dev/tpm{rm0} will flush the session. */ + attributes |= TPM2_SA_CONTINUE_SESSION; + /* * The Architecture Guide requires us to strip trailing zeros * before computing the HMAC @@ -484,7 +487,8 @@ static void tpm2_KDFe(u8 z[EC_PT_SZ], const char *str, u8 *pt_u, u8 *pt_v, sha256_final(&sctx, out); } -static void tpm_buf_append_salt(struct tpm_buf *buf, struct tpm_chip *chip) +static void tpm_buf_append_salt(struct tpm_buf *buf, struct tpm_chip *chip, + struct tpm2_auth *auth) { struct crypto_kpp *kpp; struct kpp_request *req; @@ -543,7 +547,7 @@ static void tpm_buf_append_salt(struct tpm_buf *buf, struct tpm_chip *chip) sg_set_buf(&s[0], chip->null_ec_key_x, EC_PT_SZ); sg_set_buf(&s[1], chip->null_ec_key_y, EC_PT_SZ); kpp_request_set_input(req, s, EC_PT_SZ*2); - sg_init_one(d, chip->auth->salt, EC_PT_SZ); + sg_init_one(d, auth->salt, EC_PT_SZ); kpp_request_set_output(req, d, EC_PT_SZ); crypto_kpp_compute_shared_secret(req); kpp_request_free(req); @@ -554,8 +558,7 @@ static void tpm_buf_append_salt(struct tpm_buf *buf, struct tpm_chip *chip) * This works because KDFe fully consumes the secret before it * writes the salt */ - tpm2_KDFe(chip->auth->salt, "SECRET", x, chip->null_ec_key_x, - chip->auth->salt); + tpm2_KDFe(auth->salt, "SECRET", x, chip->null_ec_key_x, auth->salt); out: crypto_free_kpp(kpp); @@ -853,7 +856,9 @@ int tpm_buf_check_hmac_response(struct tpm_chip *chip, struct tpm_buf *buf, if (rc) /* manually close the session if it wasn't consumed */ tpm2_flush_context(chip, auth->handle); - memzero_explicit(auth, sizeof(*auth)); + + kfree_sensitive(auth); + chip->auth = NULL; } else { /* reset for next use */ auth->session = TPM_HEADER_SIZE; @@ -881,7 +886,8 @@ void tpm2_end_auth_session(struct tpm_chip *chip) return; tpm2_flush_context(chip, auth->handle); - memzero_explicit(auth, sizeof(*auth)); + kfree_sensitive(auth); + chip->auth = NULL; } EXPORT_SYMBOL(tpm2_end_auth_session); @@ -962,16 +968,20 @@ static int tpm2_load_null(struct tpm_chip *chip, u32 *null_key) */ int tpm2_start_auth_session(struct tpm_chip *chip) { + struct tpm2_auth *auth; struct tpm_buf buf; - struct tpm2_auth *auth = chip->auth; - int rc; u32 null_key; + int rc; - if (!auth) { - dev_warn_once(&chip->dev, "auth session is not active\n"); + if (chip->auth) { + dev_warn_once(&chip->dev, "auth session is active\n"); return 0; } + auth = kzalloc(sizeof(*auth), GFP_KERNEL); + if (!auth) + return -ENOMEM; + rc = tpm2_load_null(chip, &null_key); if (rc) goto out; @@ -992,7 +1002,7 @@ int tpm2_start_auth_session(struct tpm_chip *chip) tpm_buf_append(&buf, auth->our_nonce, sizeof(auth->our_nonce)); /* append encrypted salt and squirrel away unencrypted in auth */ - tpm_buf_append_salt(&buf, chip); + tpm_buf_append_salt(&buf, chip, auth); /* session type (HMAC, audit or policy) */ tpm_buf_append_u8(&buf, TPM2_SE_HMAC); @@ -1014,10 +1024,13 @@ int tpm2_start_auth_session(struct tpm_chip *chip) tpm_buf_destroy(&buf); - if (rc) - goto out; + if (rc == TPM2_RC_SUCCESS) { + chip->auth = auth; + return 0; + } - out: +out: + kfree_sensitive(auth); return rc; } EXPORT_SYMBOL(tpm2_start_auth_session); @@ -1367,10 +1380,6 @@ int tpm2_sessions_init(struct tpm_chip *chip) return rc; } - chip->auth = kmalloc(sizeof(*chip->auth), GFP_KERNEL); - if (!chip->auth) - return -ENOMEM; - return rc; } EXPORT_SYMBOL(tpm2_sessions_init);